A pair of narrow, parallel slits separated by 0.250 mm is illuminated by the green component from

Question:

A pair of narrow, parallel slits separated by 0.250 mm is illuminated by the green component from a mercury vapor lamp (λ = 546.1 nm). The interference pattern is observed on a screen 1.20 m from the plane of the parallel slits. Calculate the distance
(a) From the central maximum to the first bright region on either side of the central maximum and
(b) Between the first and second dark bands in the interference pattern.